acpi: Support generation of I2C descriptor

Add a function to write a GPIO descriptor to the generated ACPI code.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/i2c/sandbox_i2c.c

@@ -11,6 +11,7 @@
 #include <i2c.h>
 #include <log.h>
 #include <asm/test.h>
+#include <dm/acpi.h>
 #include <dm/lists.h>
 #include <dm/device-internal.h>
 
@@ -83,6 +84,15 @@ static int sandbox_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
 	return ops->xfer(emul, msg, nmsgs);
 }
 
+static int sandbox_i2c_get_name(const struct udevice *dev, char *out_name)
+{
+	return acpi_copy_name(out_name, "SI2C");
+}
+
+struct acpi_ops sandbox_i2c_acpi_ops = {
+	.get_name	= sandbox_i2c_get_name,
+};
+
 static const struct dm_i2c_ops sandbox_i2c_ops = {
 	.xfer		= sandbox_i2c_xfer,
 };
@@ -98,4 +108,5 @@ U_BOOT_DRIVER(i2c_sandbox) = {
 	.of_match = sandbox_i2c_ids,
 	.ops	= &sandbox_i2c_ops,
 	.priv_auto_alloc_size = sizeof(struct sandbox_i2c_priv),
+	ACPI_OPS_PTR(&sandbox_i2c_acpi_ops)
 };

drivers/rtc/sandbox_rtc.c

@@ -9,6 +9,7 @@
 #include <i2c.h>
 #include <rtc.h>
 #include <asm/rtc.h>
+#include <dm/acpi.h>
 
 #define REG_COUNT 0x80
 
@@ -67,6 +68,17 @@ static int sandbox_rtc_write8(struct udevice *dev, unsigned int reg, int val)
 	return dm_i2c_reg_write(dev, reg, val);
 }
 
+#if CONFIG_IS_ENABLED(ACPIGEN)
+static int sandbox_rtc_get_name(const struct udevice *dev, char *out_name)
+{
+	return acpi_copy_name(out_name, "RTCC");
+}
+
+struct acpi_ops sandbox_rtc_acpi_ops = {
+	.get_name	= sandbox_rtc_get_name,
+};
+#endif
+
 static const struct rtc_ops sandbox_rtc_ops = {
 	.get = sandbox_rtc_get,
 	.set = sandbox_rtc_set,
@@ -85,4 +97,5 @@ U_BOOT_DRIVER(rtc_sandbox) = {
 	.id	= UCLASS_RTC,
 	.of_match = sandbox_rtc_ids,
 	.ops	= &sandbox_rtc_ops,
+	ACPI_OPS_PTR(&sandbox_rtc_acpi_ops)
 };

include/acpi/acpi_device.h

@@ -9,6 +9,7 @@
 #ifndef __ACPI_DEVICE_H
 #define __ACPI_DEVICE_H
 
+#include <i2c.h>
 #include <linux/bitops.h>
 
 struct acpi_ctx;
@@ -183,6 +184,26 @@ struct acpi_gpio {
 	enum acpi_gpio_polarity polarity;
 };
 
+/* ACPI Descriptors for Serial Bus interfaces */
+#define ACPI_SERIAL_BUS_TYPE_I2C		1
+#define ACPI_I2C_SERIAL_BUS_REVISION_ID		1 /* TODO: upgrade to 2 */
+#define ACPI_I2C_TYPE_SPECIFIC_REVISION_ID	1
+
+/**
+ * struct acpi_i2c - representation of an ACPI I2C device
+ *
+ * @address: 7-bit or 10-bit I2C address
+ * @mode_10bit: Which address size is used
+ * @speed: Bus speed in Hz
+ * @resource: Resource name for the I2C controller
+ */
+struct acpi_i2c {
+	u16 address;
+	enum i2c_address_mode mode_10bit;
+	enum i2c_speed_rate speed;
+	const char *resource;
+};
+
 /**
  * acpi_device_path() - Get the full path to an ACPI device
  *
@@ -270,4 +291,16 @@ int acpi_device_write_gpio_desc(struct acpi_ctx *ctx,
 int acpi_device_write_interrupt_or_gpio(struct acpi_ctx *ctx,
 					struct udevice *dev, const char *prop);
 
+/**
+ * acpi_device_write_i2c_dev() - Write an I2C device to ACPI
+ *
+ * This creates a I2cSerialBus descriptor for an I2C device, including
+ * information ACPI needs to use it.
+ *
+ * @ctx: ACPI context pointer
+ * @dev: I2C device to write
+ * @return I2C address of device if OK, -ve on error
+ */
+int acpi_device_write_i2c_dev(struct acpi_ctx *ctx, const struct udevice *dev);
+
 #endif

lib/acpi/acpi_device.c

@@ -385,3 +385,110 @@ int acpi_device_write_interrupt_or_gpio(struct acpi_ctx *ctx,
 
 	return pin;
 }
+
+/* ACPI 6.3 section 6.4.3.8.2.1 - I2cSerialBus() */
+static void acpi_device_write_i2c(struct acpi_ctx *ctx,
+				  const struct acpi_i2c *i2c)
+{
+	void *desc_length, *type_length;
+
+	/* Byte 0: Descriptor Type */
+	acpigen_emit_byte(ctx, ACPI_DESCRIPTOR_SERIAL_BUS);
+
+	/* Byte 1+2: Length (filled in later) */
+	desc_length = largeres_write_len_f(ctx);
+
+	/* Byte 3: Revision ID */
+	acpigen_emit_byte(ctx, ACPI_I2C_SERIAL_BUS_REVISION_ID);
+
+	/* Byte 4: Resource Source Index is Reserved */
+	acpigen_emit_byte(ctx, 0);
+
+	/* Byte 5: Serial Bus Type is I2C */
+	acpigen_emit_byte(ctx, ACPI_SERIAL_BUS_TYPE_I2C);
+
+	/*
+	 * Byte 6: Flags
+	 *  [7:2]: 0 => Reserved
+	 *    [1]: 1 => ResourceConsumer
+	 *    [0]: 0 => ControllerInitiated
+	 */
+	acpigen_emit_byte(ctx, 1 << 1);
+
+	/*
+	 * Byte 7-8: Type Specific Flags
+	 *   [15:1]: 0 => Reserved
+	 *      [0]: 0 => 7bit, 1 => 10bit
+	 */
+	acpigen_emit_word(ctx, i2c->mode_10bit);
+
+	/* Byte 9: Type Specific Revision ID */
+	acpigen_emit_byte(ctx, ACPI_I2C_TYPE_SPECIFIC_REVISION_ID);
+
+	/* Byte 10-11: I2C Type Data Length */
+	type_length = largeres_write_len_f(ctx);
+
+	/* Byte 12-15: I2C Bus Speed */
+	acpigen_emit_dword(ctx, i2c->speed);
+
+	/* Byte 16-17: I2C Slave Address */
+	acpigen_emit_word(ctx, i2c->address);
+
+	/* Fill in Type Data Length */
+	largeres_fill_len(ctx, type_length);
+
+	/* Byte 18+: ResourceSource */
+	acpigen_emit_string(ctx, i2c->resource);
+
+	/* Fill in I2C Descriptor Length */
+	largeres_fill_len(ctx, desc_length);
+}
+
+/**
+ * acpi_device_set_i2c() - Set up an ACPI I2C struct from a device
+ *
+ * The value of @scope is not copied, but only referenced. This implies the
+ * caller has to ensure it stays valid for the lifetime of @i2c.
+ *
+ * @dev: I2C device to convert
+ * @i2c: Place to put the new structure
+ * @scope: Scope of the I2C device (this is the controller path)
+ * @return chip address of device
+ */
+static int acpi_device_set_i2c(const struct udevice *dev, struct acpi_i2c *i2c,
+			       const char *scope)
+{
+	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
+	struct udevice *bus = dev_get_parent(dev);
+
+	memset(i2c, '\0', sizeof(*i2c));
+	i2c->address = chip->chip_addr;
+	i2c->mode_10bit = 0;
+
+	/*
+	 * i2c_bus->speed_hz is set if this device is probed, but if not we
+	 * must use the device tree
+	 */
+	i2c->speed = dev_read_u32_default(bus, "clock-frequency",
+					  I2C_SPEED_STANDARD_RATE);
+	i2c->resource = scope;
+
+	return i2c->address;
+}
+
+int acpi_device_write_i2c_dev(struct acpi_ctx *ctx, const struct udevice *dev)
+{
+	char scope[ACPI_PATH_MAX];
+	struct acpi_i2c i2c;
+	int ret;
+
+	ret = acpi_device_scope(dev, scope, sizeof(scope));
+	if (ret)
+		return log_msg_ret("scope", ret);
+	ret = acpi_device_set_i2c(dev, &i2c, scope);
+	if (ret < 0)
+		return log_msg_ret("set", ret);
+	acpi_device_write_i2c(ctx, &i2c);
+
+	return ret;
+}

test/dm/acpigen.c

@@ -276,3 +276,35 @@ static int dm_test_acpi_interrupt_or_gpio(struct unit_test_state *uts)
 }
 DM_TEST(dm_test_acpi_interrupt_or_gpio,
 	DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test emitting an I2C descriptor */
+static int dm_test_acpi_i2c(struct unit_test_state *uts)
+{
+	struct acpi_ctx *ctx;
+	struct udevice *dev;
+	u8 *ptr;
+
+	ut_assertok(alloc_context(&ctx));
+
+	ptr = acpigen_get_current(ctx);
+
+	ut_assertok(uclass_get_device(UCLASS_RTC, 0, &dev));
+	ut_asserteq(0x43, acpi_device_write_i2c_dev(ctx, dev));
+	ut_asserteq(28, acpigen_get_current(ctx) - ptr);
+	ut_asserteq(ACPI_DESCRIPTOR_SERIAL_BUS, ptr[0]);
+	ut_asserteq(25, get_unaligned((u16 *)(ptr + 1)));
+	ut_asserteq(ACPI_I2C_SERIAL_BUS_REVISION_ID, ptr[3]);
+	ut_asserteq(0, ptr[4]);
+	ut_asserteq(ACPI_SERIAL_BUS_TYPE_I2C, ptr[5]);
+	ut_asserteq(0, get_unaligned((u16 *)(ptr + 7)));
+	ut_asserteq(ACPI_I2C_TYPE_SPECIFIC_REVISION_ID, ptr[9]);
+	ut_asserteq(6, get_unaligned((u16 *)(ptr + 10)));
+	ut_asserteq(100000, get_unaligned((u32 *)(ptr + 12)));
+	ut_asserteq(0x43, get_unaligned((u16 *)(ptr + 16)));
+	ut_asserteq_str("\\_SB.I2C0", (char *)ptr + 18);
+
+	free_context(&ctx);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_i2c, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);